A multi-purpose bracket which clamps across both gunwales of a canoe and presents a standardized pad at each side of the hull to align precisely and mount rigidly a variety of accessories is known from U.S. Pat. No. 5,501,169. These accessories include multi-hull catamaran coupling bars, portaging wheels, and any other equipment requiring a temporary but strong and secure means of attachment. In particular, see FIG. 8 thereof with two canoes coupled together in a catamaran configuration by a coupling bar assembly.
Similarly, a watercraft attachment device is known from U.S. Pat. No. 8,074,593 in which two watercrafts are joined using a first pair of parallel tubes that are parallel to the watercrafts and a second pair of parallel tubes that are perpendicular to and adjoin the first pair of parallel tubes and are hooked with hook attachments extending from each corner over a lip of each cockpit within the watercrafts to connect the watercrafts and then may include tensioning cords to tighten the hook attachments to secure the watercraft attachment device in place.
A canoe platform is known from U.S. Pat. No. 6,725,798 that interconnects a pair of spaced apart canoes arranged parallel with each other so that the platform can support human activity while the canoes support the platform above the water. The platform is made of a pair of panels adjoining each other and spanning the gunwales of the canoes and the space between them.